Adaptive headlamp system for vehicles

ABSTRACT

A vehicle headlamp system includes a vehicle supported power and control system including a data bus. A sensor module can be connected to the data bus to provide information related to environmental conditions or information relating to presence and position of other vehicles and pedestrians. A separate headlamp controller can be connected to the vehicle supported power and control system and the sensor module through the bus. The headlamp controller can include an image frame buffer that can refresh held images at greater than 30 Hz speed. An active LED pixel array can be connected to the headlamp controller to project light according to a pattern and intensity defined by the image held in the image frame buffer and a standby image buffer can be connected to the image frame buffer to hold a default image.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit of priority to European Patent Application No. 18201763.2 filed Oct. 22, 2018 and to U.S. Provisional Patent Application No. 62/729,298 filed Sep. 10, 2018, each of which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates generally to a system providing dynamic lighting control for vehicle headlamps. In certain embodiments, the system can be LED pixel array able to provide an intensity and spatially modulated light projection suitable for adaptive driving beam systems.

BACKGROUND

A night-time vehicle driver may use a low directed headlight beam pattern to prevent drivers of oncoming vehicles from being dazzled or subjected to safety impairing glare, while switching to a high directed beam with greater range for improved roadway illumination when oncoming vehicles are not present. However, a driver of the vehicle can inadvertently drive with the high directed beam pattern if they fail to see an oncoming vehicle. Fortunately, widespread availability of sensor technologies for driver assist or autonomous operation have also enabled systems that provide active control of vehicle headlamp road illumination. Instead of relying on a fixed or user controlled illumination pattern, a headlight beam can be automatically dimmed or redirected based on inputs from the vehicle and/or its surroundings. For example, oncoming vehicles can be identified, and a portion of the headlight beam redirected to limit potential glare. As another example, pedestrian detection or location positioning systems can be used to identify areas likely to have pedestrians, and headlight beams redirected to illuminate pedestrian activity. Such adaptive driving beam (ADB) systems have been developed using mechanical shields, LEDs, digital micromirrors, and LCD shuttering systems.

Unfortunately, supporting large active arrays of LEDs or other light emitter/redirection systems (e.g. digital micromirrors or scanning lasers) can be difficult. Individual light intensity of thousands of pixels may need to be controlled at refresh rates of 30-60 Hz. Systems able to reliably handle such data rates are needed.

SUMMARY

In one embodiment, a vehicle headlamp system includes a vehicle supported power and control system including a data bus. A sensor module can be connected to the data bus to provide information related to environmental conditions (e.g. time of day or weather conditions) or information relating to presence and position of other vehicles and pedestrians. A separate headlamp controller can be connected to the vehicle supported power and control system and the sensor module through the bus. The headlamp controller can include an image frame buffer that can refresh held images at greater than 30 Hz speed. An active LED pixel array can be connected to the headlamp controller to project light according to a pattern and intensity defined by the image held in the image frame buffer and a standby image buffer can be connected to the image frame buffer to hold a default image.

In one embodiment, the vehicle supported power and control system provides image data to the headlamp controller. Alternatively, images can be generated by the headlamp controller in response to data received from the vehicle supported power and control system. In operation, the LED pixel array can be directed to reduce light emitted toward an oncoming vehicle.

In some embodiments, each pixel in the LED pixel array is addressable, while in other embodiments, fixed pixel groupings (e.g. 5×5 pixel blocks) are addressable. The aspect ratio of the LED pixel array can be selectable. In some embodiments the LED pixel array is positioned adjacent to static LED lighting.

In some embodiments the frame buffer is connected to the active LED pixel array through a pulse width modulator. To be able to timely respond to changes in lighting requirements for vehicles moving at highway speeds, the image frame buffer can refresh held images at 60 Hz or greater speed.

In another embodiment, a headlamp controller (suitable for working in conjunction with a vehicles power and sensor system) can include an image frame buffer that can refresh held images at greater than 30 Hz speed. The headlamp controller can be connected to an active LED pixel array with individually addressable pixels connected to the headlamp controller to project light according to a pattern and intensity defined by the image held in the image frame buffer. In some embodiment a standby image buffer can be connected to the image frame buffer to hold a default image.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating illumination of a road in discrete sectors using an active headlamp;

FIG. 2 illustrates a dynamic pixel addressable lighting module positioned adjacent to a static lighting module;

FIG. 3A is one embodiment of a vehicle headlamp system for controlling an active headlamp;

FIG. 3B is one embodiment of a vehicle headlamp system for controlling an active headlamp with connections to vehicle processing output; and

FIG. 4 is a schematic illustration of one embodiment of an active headlamp controller.

DETAILED DESCRIPTION

Light emitting pixel arrays may support applications that benefit from fine-grained intensity, spatial, and temporal control of light distribution. This may include, but is not limited to, precise spatial patterning of emitted light from pixel blocks or individual pixels. Depending on the application, emitted light may be spectrally distinct, adaptive over time, and/or environmentally responsive. The light emitting pixel arrays may provide pre-programmed light distribution in various intensity, spatial, or temporal patterns. The emitted light may be based at least in part on received sensor data and may be used for optical wireless communications. Associated optics may be distinct at a pixel, pixel block, or device level. An example light emitting pixel array may include a device having a commonly controlled central block of high intensity pixels with an associated common optic, whereas edge pixels may have individual optics. Common applications supported by light emitting pixel arrays include video lighting, automotive headlights, architectural and area illumination, street lighting, and informational displays.

Light emitting pixel arrays may be used to selectively and adaptively illuminate buildings or areas for improved visual display or to reduce lighting costs. In addition, light emitting pixel arrays may be used to project media facades for decorative motion or video effects. In conjunction with tracking sensors and/or cameras, selective illumination of areas around pedestrians may be possible. Spectrally distinct pixels may be used to adjust the color temperature of lighting, as well as support wavelength specific horticultural illumination.

Street lighting is an important application that may greatly benefit from use of light emitting pixel arrays. A single type of light emitting array may be used to mimic various street light types, allowing, for example, switching between a Type I linear street light and a Type IV semicircular street light by appropriate activation or deactivation of selected pixels. In addition, street lighting costs may be lowered by adjusting light beam intensity or distribution according to environmental conditions or time of use. For example, light intensity and area of distribution may be reduced when pedestrians are not present. If pixels of the light emitting pixel array are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions.

Light emitting arrays are also well suited for supporting applications requiring direct or projected displays. For example, warning, emergency, or informational signs may all be displayed or projected using light emitting arrays. This allows, for example, color changing or flashing exit signs to be projected. If a light emitting array is composed of a large number of pixels, textual or numerical information may be presented. Directional arrows or similar indicators may also be provided.

Vehicle headlamps are a light emitting array application that requires large pixel numbers and a high data refresh rate. Automotive headlights that actively illuminate only selected sections of a roadway can used to reduce problems associated with glare or dazzling of oncoming drivers. Using infrared cameras as sensors, light emitting pixel arrays activate only those pixels needed to illuminate the roadway, while deactivating pixels that may dazzle pedestrians or drivers of oncoming vehicles. In addition, off-road pedestrians, animals, or signs may be selectively illuminated to improve driver environmental awareness. If pixels of the light emitting pixel array are spectrally distinct, the color temperature of the light may be adjusted according to respective daylight, twilight, or night conditions. Some pixels may be used for optical wireless vehicle to vehicle communication.

One high value application for light emitting arrays is illustrated with respect to FIG. 1, which shows potential roadway illumination pattern 100 for a vehicle headlamp system illuminating a region 120 in front of a vehicle. As illustrated, a roadway 110 includes a left edge 112, a right edge 114, and a centerline 116. In this example, two major regions are illuminated—a downward directed statically illuminated region 122 and a dynamically illuminated region 130. Light intensity within region 130 can be dynamically controlled. For example, as an oncoming vehicle (not shown) traveling between centerline 116 and left edge 112 moves into a subregion 132, light intensity can be reduced or shut off completely. As the oncoming vehicle moves toward subregion 134, a series of subregions (not shown) can be defined to also have reduced light intensity, reducing the chance of unsafe dazzle or glare. As will be appreciated, in other embodiments, light intensity can be increased to accentuate road signs or pedestrians, or spatial illumination patterns adjusted to allow, for example, dynamic light tracking of curved roadways.

FIG. 2 illustrates a positioning of lighting modules 200 able to provide a lighting pattern such as discussed with respect to FIG. 1. An LED light module 222 can include LEDS, alone or in conjunction with primary or secondary optics, including lenses or reflectors. To reduce overall data management requirements, the light module 222 can be limited to on/off functionality or switching between relatively few light intensity levels. Pixel level control of light intensity is not necessarily supported.

Positioned adjacent to LED light module 22 is an active LED array 230. The LED array includes a CMOS die 202, with a pixel area 204 and alternatively selectable LED areas 206 and 208. The pixel area 204 can have 104 rows and 304 columns, for a total of 31,616 pixels distributed over an area of 12.2 by 4.16 millimeters. The selectable LED areas 206 and 208 allow for differing aspect ratios suitable for different vehicle headlamps or applications to be selected. For example, in one embodiment selectable LED area 206 can have a 1:3 aspect ratio with 82 rows and 246 columns, for a total of 20,172 pixels distributed over an area of 10.6 by 4 millimeters. Alternatively, selectable LED area 208 can have a 1:4 aspect ratio with 71 rows and 284 columns, for a total of 20,164 pixels distributed over an area of 12.1 by 3.2 millimeters. In one embodiment, pixels can be actively managed to have a 10-bit intensity range and a refresh rate of between 30 and 100 Hz, with a typical operational refresh rate of 60 Hz or greater.

FIG. 3A illustrates an embodiment of a vehicle headlamp system 300 including a vehicle supported power (302) and control system including a data bus (304). A sensor module 306 can be connected to the data bus 304 to provide data related to environment conditions (e.g. time of day, rain, fog, ambient light levels, etc), vehicle condition (parked, in-motion, speed, direction), or presence/position of other vehicles or pedestrians. A separate headlamp controller 330 can be connected to the vehicle supported power and control system.

The vehicle headlamp system 300 can include a power input filter and control module 310. The module 310 can support various filters to reduce conducted emissions and provide power immunity. Electrostatic discharge (ESD) protection, load-dump protection, alternator field decay protection, and reverse polarity protection can also be provided by module 310.

Filtered power can be provided to a LED DC/DC module 312. Module 312 can be used only for powering LEDs, and typically has an input voltage of between 7 and 18 volts, with a nominal 13.2 volts. Output voltage can be set to be slightly higher (e.g. 0.3 volts) than LED array max voltage as determined by factory or local calibration, and operating condition adjustments due to load, temperature or other factors.

Filtered power is also provided to a logic LDO module 314 that can be used to power microcontroller 322 or CMOS logic in the active headlamp 330.

The vehicle headlamp system 300 can also include a bus transceiver 320 (e.g. with a UART or SPI interface) connected to microcontroller 322. The microcontroller 322 can translate vehicle input based on or including data from the sensor module 306. The translated vehicle input can include a video signal that is transferrable to an image buffer in the active headlamp module 324. In addition, the microcontroller 322 can load default image frames and test for open/short pixels during startup. In one embodiment, a SPI Interface loads an image buffer in CMOS. Image frames can be full frame, differential or partial. Other microcontroller 322 features can include control interface monitors of CMOS status, including die temperature, as well as logic LDO output. In some embodiments, LED DC/DC output can be dynamically controlled to minimize headroom. In addition to providing image frame data, other headlamp functions such as complementary use in conjunction with side marker or turn signal lights, and/or activation of daytime running lights can also be controlled.

FIG. 3B illustrates one embodiment of various components and modules of a vehicle headlamp system 330 capable of accepting vehicle sensor inputs and commands, as well as commands based on headlamp or locally mounted sensors. As seen in FIG. 3B, vehicle mounted systems can include remote sensors 340 and electronic processing modules capable of sensor processing 342. Processed sensor data can be input to various decision algorithms in a decision algorithm module 344 that result in command instructions or pattern creation based at least in part on various sensor input conditions, for example, such as ambient light levels, time of day, vehicle location, location of other vehicles, road conditions, or weather conditions. As will be appreciated, useful information for the decision algorithm module 344 can be provided from other sources as well, including connections to user smartphones, vehicle to vehicle wireless connections, or connection to remote data or information resources.

Based on the results of the decision algorithm module 344, image creation module 346 provides an image pattern that will ultimately provide an active illumination pattern to the vehicle headlamp that is dynamically adjustable and suitable for conditions. This created image pattern can be encoded for serial or other transmission scheme by image coding module 348 and sent over a high speed bus 350 to an image decoding module 354. Once decoded, the image pattern is provided to the uLED module 380 to drive activation and intensity of illumination pixels.

In some operational modes, the system 330 can be driven with default or simplified image patterns using instructions provided to a headlamp control module 370 via connection of the decision algorithm module 344 through a CAN bus 352. For example, an initial pattern on vehicle start may be a uniform, low light intensity pattern. In some embodiments, the headlamp control module can be used to drive other functions, including sensor activation or control.

In other possible operational modes, the system 330 can be driven with image patterns derived from local sensors or commands not requiring input via the CAN bus 352 or high speed bus 350. For example, local sensors 360 and electronic processing modules capable of sensor processing 362 can be used. Processed sensor data can be input to various decision algorithms in a decision algorithm module 364 that result in command instructions or pattern creation based at least in part on various sensor input conditions, for example, such as ambient light levels, time of day, vehicle location, location of other vehicles, road conditions, or weather conditions. As will be appreciated, like vehicle supported remote sensors 340, useful information for the decision algorithm module 364 can be provided from other sources as well, including connections to user smartphones, vehicle to vehicle wireless connections, or connection to remote data or information resources.

Based on the results of the decision algorithm module 364, image creation module 366 provides an image pattern that will ultimately provide an active illumination pattern to the vehicle headlamp that is dynamically adjustable and suitable for conditions. In some embodiments, this created image pattern does not require additional image coding/decoding steps but can be directly sent to the uLED module 380 to drive illumination of selected pixels.

FIG. 4 illustrates one embodiment of various components and modules of an active headlamp system 400 such as described with respect to active headlamp 324 of FIG. 3A. As illustrated, internal modules include an LED power distribution and monitor module 410 and a logic and control module 420.

Image or other data from the vehicle can arrive via an SPI interface 412. Successive images or video data can be stored in an image frame buffer 414. If no image data is available, one or more standby images held in a standby image buffer can be directed to the image frame buffer 414. Such standby images can include, for example, an intensity and spatial pattern consistent with legally allowed low beam headlamp radiation patterns of a vehicle.

In operation, pixels in the images are used to define response of corresponding LED pixels in the pixel module 430, with intensity and spatial modulation of LED pixels being based on the image(s). To reduce data rate issues, groups of pixels (e.g. 5×5 blocks) can be controlled as single blocks in some embodiments. High speed and high data rate operation is supported, with pixel values from successive images able to be loaded as successive frames in an image sequence at a rate between 30 Hz and 100 Hz, with 60 Hz being typical. In conjunction with a pulse width modulation module 418, each pixel in the pixel module can be operated to emit light in a pattern and with an intensity at least partially dependent on the image held in the image frame buffer 414.

In one embodiment, intensity can be separately controlled and adjusted by setting appropriate ramp times and pulse width for each LED pixel using logic and control module 420 and the pulse width modulation module 418. This allows staging of LED pixel activation to reduce power fluctuations, and to provide various pixel diagnostic functionality.

Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims. It is also understood that other embodiments of this invention may be practiced in the absence of an element/step not specifically disclosed herein. 

1. A vehicle headlamp system, comprising: a vehicle supported power and control system including a data bus; a sensor module connected to the data bus; a separate headlamp controller connected to the vehicle supported power and control system and the sensor module through the bus, the headlamp controller having an image frame buffer that can refresh held images at greater than 30 Hz speed; an active LED pixel array connected to the headlamp controller to project light according to a pattern and intensity defined by images held in the image frame buffer; and a standby image buffer connected to the image frame buffer to hold a default image.
 2. The vehicle headlamp system of claim 1, wherein the vehicle supported power and control system provides image data to the headlamp controller.
 3. The vehicle headlamp system of claim 1, wherein the sensor module can be used to identify oncoming vehicles and select an image to be sent the headlamp controller.
 4. The vehicle headlamp system of claim 1, wherein the LED pixel array can be directed to reduce light emitted toward an oncoming vehicle.
 5. The vehicle headlamp system of claim 1, wherein each pixel in the LED pixel array is addressable.
 6. The vehicle headlamp system of claim 1, wherein aspect ratio of the LED pixel array is selectable.
 7. The vehicle headlamp system of claim 1, wherein the LED pixel array is positioned adjacent to static LED lighting.
 8. The vehicle headlamp system of claim 1, wherein the frame buffer is connected to the active LED pixel array through a pulse width modulator.
 9. The vehicle headlamp system of claim 1, wherein the image frame buffer can refresh held images at 60 Hz or greater speed.
 10. A vehicle headlamp system, comprising: a headlamp controller having an image frame buffer that can refresh held images at greater than 30 Hz speed; an active LED pixel array with individually addressable pixels connected to the headlamp controller to project light according to a pattern and intensity defined by the image held in the image frame buffer; a standby image buffer connected to the image frame buffer to hold a default image.
 11. The vehicle headlamp system of claim 10, wherein the controller is attached through a data bus to a vehicle supported power and control system that provides at least some images to the image frame buffer.
 12. The vehicle headlamp system of claim 10, further comprising a sensor module usable in conjunction with a vehicle supported power and control system to identify position of oncoming vehicles.
 13. The vehicle headlamp system of claim 10, wherein each pixel in the LED pixel array is addressable.
 14. The vehicle headlamp system of claim 10, wherein aspect ratio of the LED pixel array is selectable.
 15. The vehicle headlamp system of claim 10, wherein the LED pixel array is positioned adjacent to static LED lighting.
 16. The vehicle headlamp system of claim 10, wherein the frame buffer is connected to the active LED pixel array through a pulse width modulator.
 17. The vehicle headlamp system of claim 10, wherein the image frame buffer can refresh held images at 60 Hz or greater speed. 